Each year in the U.S. nearly 500,000 babies are born prematurely. Premature births are a leading cause of long-term neurologic disabilities in children and cost more than $26 billion per year. Premature infants are cared for in the neonatal intensive care unit (NICU) where more than 33,000 develop a healthcare associated infection (HAI). HAIs are estimated to result in $28-45 billion in healthcare costs annually. In addition to the short-term costs of HAIs, neonatal infections contribute to devastating neurologic disabilities and poor growth outcomes. Staphylococcus aureus (S. aureus) is the second most common pathogen causing HAIs in neonates. Out of 57,000 very low birth weight infants, an estimated 3.7% develop bloodstream or central nervous system S. aureus infections annually with an attributable mortality of 25%. Despite aggressive measures to prevent S. aureus infections in neonates, the burden of S. aureus disease remains high in this population. We propose a new paradigm to prevent S. aureus HAIs in neonates. Parents, rather than healthcare workers, may be a key reservoir from which neonates acquire S. aureus colonization in the NICU. This finding is consistent with a changing NICU environment where skin-to-skin contact between parents and neonates is encouraged and may promote S. aureus transmission, while at the same time, common hospital infection prevention measures have reduced healthcare worker transmission of S. aureus. The long term objective of this proposal is to prevent HAIs in neonates, especially those caused to S. aureus. The specific aims are Aim 1) to assess S. aureus colonization and strain concordance amongst parents and neonates in the NICU, Aim 2) to measure the effect of treating parents with short course intranasal mupirocin and topical chlorhexidine antisepsis on acquisition of S. aureus colonization in neonates in a randomized controlled trial. We will assemble a cohort of neonates admitted to the NICU and their parents and follow them longitudinally to measure acquisition of S. aureus colonization in neonates in the NICU and determine the role of parents in postnatal S. aureus transmission. Some neonate-parent pairs will be randomized, and parents will receive treatment or control to eradicate S. aureus colonization. The findings of this proposal could change the paradigm of HAI prevention in the NICU from one that focuses on healthcare workers and the environment to one that recognizes parents and visitor as important sources of exposure to pathogens that contribute to HAIs.